This video shows what I did to fix an OptiPlex 780 (Small Form Factor)
The computer would display a flashing amber power button light. (It didn’t flash anymore when I took the video but you get the idea). Usually on Dell computers, this amber flashing means a bad motherboard or bad power supply.
The first thing to do is to get a working power supply. I did not have one for this specific dell computer so that I took apart the power supply and effectively, it had damaged capacitors.
It is just easier to replace the whole power supply but I decided to replace the bad capacitors just for demonstration.
Whenever doing soldering, use a fan and avoid the fumes that result from the flux and solder.
Here are the capacitors that were replaced: